Pressure sensitive adhesives are useful for the joining of two materials. The interfaces between the adhesive and the materials are vital to the performance of the joined materials. The loss of adhesion at either interface can doom the usage of the materials. Adhesives have been structured in the past for various reasons.
Several approaches to structuring adhesives are known, including those shown in, for example, U.S. Pat. Nos. 5,296,277 and 5,362,516 (both Wilson et al.); U.S. Pat. No. 5,141,790 and U.S. Pat. No. 5,897,930 (both Calhoun et al.); and U.S. Pat. No. 6,197,397 (Sher et. al). These patents disclose how the structure in the adhesive is built from the interface between the adhesive and the release liner.
These release liners are generally manufactured by structuring a thermoplastic polymer surface of the liner. Current methods of making release liners having microstructured patterns include cast extrusion onto a microstructured tool that imparts the desired pattern to the liner followed by silicone release coating where required, or by pressing a pattern into a thermoplastic polymer surface, with or without a silicone release coating, between structured nips to impart a pattern. These manufacturing steps form the topography on the liner, which is then used to impart topography into an adhesive. These steps require durable patterned tools, appropriate equipment, and materials suitable for these processes that can provide stable topography for further processing and use.